Chimpanzee locomotor energetics and the origin of human bipedalism

Michael D. Sockol, David A Raichlen, Herman Pontzer

Research output: Contribution to journalArticle

175 Citations (Scopus)

Abstract

Bipedal walking is evident in the earliest hominins [Zollikofer CPE, Ponce de Leon MS, Lieberman DE, Guy F, Pilbeam D, et al. (2005) Nature 434:755-759], but why our unique two-legged gait evolved remains unknown. Here, we analyze walking energetics and biomechanics for adult chimpanzees and humans to investigate the long-standing hypothesis that bipedalism reduced the energy cost of walking compared with our ape-like ancestors [Rodman PS, McHenry HM (1980) Am J Phys Anthropol 52:103-106]. Consistent with previous work on juvenile chimpanzees [Taylor CR, Rowntree VJ (1973) Science 179:186-187], we find that bipedal and quadrupedal walking costs are not significantly different in our sample of adult chimpanzees. However, a more detailed analysis reveals significant differences in bipedal and quadrupedal cost in most individuals, which are masked when subjects are examined as a group. Furthermore, human walking is ≈75% less costly than both quadrupedal and bipedal walking in chimpanzees. Variation in cost between bipedal and quadrupedal walking, as well as between chimpanzees and humans, is well explained by biomechanical differences in anatomy and gait, with the decreased cost of human walking attributable to our more extended hip and a longer hindlimb. Analyses of these features in early fossil hominins, coupled with analyses of bipedal walking in chimpanzees, indicate that bipedalism in early, ape-like hominins could indeed have been less costly than quadrupedal knucklewalking.

Original languageEnglish (US)
Pages (from-to)12265-12269
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume104
Issue number30
DOIs
StatePublished - Jul 24 2007

Fingerprint

Pan troglodytes
Walking
Hominidae
Costs and Cost Analysis
Gait
Fossils
Hindlimb
Biomechanical Phenomena
Hip
Anatomy

Keywords

  • Biomechanics
  • Human evolution
  • Inverse dynamics
  • Limb length
  • Locomotion

ASJC Scopus subject areas

  • Genetics
  • General

Cite this

Chimpanzee locomotor energetics and the origin of human bipedalism. / Sockol, Michael D.; Raichlen, David A; Pontzer, Herman.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 104, No. 30, 24.07.2007, p. 12265-12269.

Research output: Contribution to journalArticle

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